The present invention relates to a collapsible tower that may be portable or may be permanently secured on location. Portability of such a tower is feasible only if the tower is capable of assuming a collapsed state during transportation. Likewise, for both the portable tower and the stationary tower, collapsibility of the tower greatly enhances the advantages of the tower due to ease of performing preventive maintenance and repair to the tower as well as replacement of items such as light bulbs used with apparatus secured to the top of the tower. Extendible or collapsible towers are presently existent and generally are mounted on a trailer, truck, platform or the like. Further, present extendible towers are generally employed to support banks of lights for illuminating construction sites, carnivals, fairgrounds and the like; to support signs for advertising, to support platforms that provide a work surface, or the like.
Heretofore, extendible towers have generally been constructed from welded sections and raised and lowered by various arrangements of a plurality of cables or the like. These towers are cumbersome, very expensive and represent definite safety hazards. The sections for example, have generally been fabricated from a plurality of structural members welded together to form a skeletal structure. Skeletal structures when extended, offer less resistance to the wind than a solid structure of the same size, but are much more expensive to fabricate. Prior towers further have assumed various geometrical shapes such as triangles, circles, rectangles, etc. and, for the most part, the geometric shapes have provided edges around which guides were employed to maintain alignment between the sections. Raising and lowering of the prior art towers has normally been accomplished by a plurality of cables either interconnected between the sections as a continuous cable or as separate cables connecting each section to the next adjacent section. Single cable systems have also been employed, but have not heretofore proved satisfactory.
All of the presently existing towers have been found to be deficient in certain respects. For example, structures used in the prior towers have dictated excessive expense in fabrication of the sections; set up and maintenance of the cable system; in the size and strength of the platform, trailer or the like required for transporting the tower, etc. Hence economics precludes feasible use of existing towers for numerous situations. Further, presently existing towers may present safety hazards during raising, lowering and while standing in the raised position. Continued application of force to the cable system after the tower has been completely raised can cause the tower to buckle and fall. Likewise, during raising and lowering, the present existing towers are dangerous.
The tower of the present invention overcomes all the problems and disadvantages of the prior towers. Specifically, the instant tower is economical to manufacture, maintenancefree, safe, efficient and easy to operate and transport. Moreover, the instant tower represents a tremendous aesthetic improvement over existing towers.
The prior art contains numerous teachings of extendible towers as exemplified by U.S. Pat. Nos. 2,576,389 to Craighead et al; 2,787,343 to Mitchell; 2,822,067 to Price; 2,948,363 to Hopfeld; 2,966,956 to Campbell et al; 3,000,473 to Reynolds; 3,009,546 to Anderson, Sr., et al; 3,266,051 to Attwood; 3,328,921 to Keslin; 3,373,473 to Keslin; 3,439,467 to Partlow, and 3,495,364 to De Bella. None of the prior art, however, either alone or in combination appears to anticipate or suggest the present invention.